First you need to install summerboard, an application that allows you install custom themes for springboard. To get to this go to installer, then to the install tab , then to the system folder to find it.

Step 2: Restart Your iPhone or iPod Touch

You must restart your device to activate summerboard. It will not work unless you do this.

Step 3: Install A Theme

An icon called "SMB Prefs" will now appear, do not use it yet. Next you need to install a theme. To do this, go to the install tab, then to "themes (summerboard)".

Step 4: Change The Theme

Go back to the homescreen and open "SMB Prefs". Next, go to the theme tab and select the theme you want to use.